Conventionally, there have been attempts to determine the absolute configuration of external ligands based on the induced Cotton effects revealed by the analysis of circular dichroism (CD) spectrophotometry. For example, the following are reported:
(1) E. Yashima, T. Matsushima, and Y. Okamoto (J. Am. Chem. Soc., 1997, 119, 6345-6359) report on polymers forming a helical structure in the presence of a chiral compound and describe that there is a good correlation between the sign of the Cotton effect in the circular dichroism spectra induced by the ligand (chiral compound) and the absolute configuration of the ligand.
However, since the helical structure is induced by the ion pair formed between the carboxylate group of the polymer side chain and the ammonium group of the ligand, this method can be used for typical monoamines and aminoalcohols but is not applicable to alcohols.
(2) X. Huang, B. H. Rickmann, B. Borhan, N. Berova, and K. Nakanishi (J. Am. Chem. Soc., 1998, 120, 6185-6186) report on circular dichroism induced in a long chain-crosslinked porphyrin diner by a chiral ligand. There is a correlation between the sign of the Cotton effect and the absolute configuration of the ligand. In this system, however, circular dichroism is induced only when one ligand molecule is concurrently coordinated to two porphyrin units. Therefore, this method is useful only for bifunctional compounds such as diamines and aminoalcohols.
(3) M. Takeuchi, T. Imada, and S. Shinkai (Bull. Chem. Soc., Jpn., 1998, 71, 1117-1123) report that a porphyrin dimer having a phenylboronic acid unit exhibits circular dichroism in the presence of a variety of sugars.
This method is applicable only to polyols (polyalcohols) which form a chemical bond with boronic acid, and it is not a method for directly determining the absolute configuration around a specific asymmetric center.
(4) H. Tsukube, M. Hosokubo, M. Wada, S. Shinoda, and H. Tamiaki (J. Chem. Soc., Dalton Trans., 1999, 11-12) report that a tris(β-diketonato) lanthanide complex exhibits circular dichroism in the presence of chiral amino alcohols. In this system, however, monoamines or monoalcohols do not induce chirality.
(5) S. Zahn, and J. W. Canary (Org. Lett., 1999, 1, 861-864) report that the absolute configuration of amino acids and aminoalcohols can be determined based on the circular dichroism of their copper complexes.
However, this method is applicable only to bidentate amino acids and aminoalcohols and can not be used for monoamines or monoalcohols.
As is clear from the above, there have been no reports about a method for determining the absolute configuration of chiral compounds having a wide variety of basic groups, such as monoalcohols.
The X-ray diffraction method is known as a method for determining the absolute configuration of chiral compounds. However, there is a limitation in that this method is applicable only to crystalline compounds.